1. Field of the Invention
The present invention relates to an active energy ray-curable ink composition.
2. Description of the Related Art
Active energy ray-curable compositions have been traditionally supplied and used for offset printing, silk screen printing, topcoat agents and the like. Particularly, the amount of use of these compositions is increasing in recent years, due to the merits of cost cutdown as a result of simplification of drying processes, a decrease in the amount of volatilization of solvents as an environmental response or the like. Among them, water-based curable compositions and solvent-based curable compositions are predominantly used as inkjet ink, and they can be sorted and used for different applications in accordance with their respective features. For industrial use, these active energy ray-curable compositions have problems that there is limitation on the recipient base material, their water resistance is relatively poor, a large amount of energy is consumed for drying of the ink, ink compositions adhere to the head due to drying, and the like. For that reason, it has been expected to replace those inkjet inks with active energy ray-curable inks which are relatively less volatile.
Active energy ray-curable inks are expected to be used with various base materials such as polyinyl chloride, polycarbonate, acrylic resin and glass. There is an increasing demand for inks that closely adhere to polypropylene (PP) or polyethylene terephthalate (PET) of those soft packaging materials used in packaging.
However, adhesion to base materials largely depends on the affinity of the monomers included in the ink and the base material, and the bonding of the polar moiety. Therefore, it is required to prepare an ink composition suitable for every base material. Furthermore, in order to use in response to various base materials, several kinds of inks suited for the base materials are required. In order to solve such problems, using isobornyl acrylate which has particularly good affinity to various base materials, can be conceived. However, isobornyl acrylate has a problem of large steric hindrance, and is prone to form a film with a low molecular weight when cured. Therefore, the cured film cannot have sufficient strength, and excellent adhesiveness cannot be obtained.
Japanese Patent Application Laid-Open No. 2007-056232 discloses an ink prepared using isobornyl acrylate and N-vinyl caprolactam, which has good stretching processability and can be suitably used in the applications where deformation processing is carried out after inkjet printing when printing is processed on flexible materials. However, the ink contains 2-hydroxy-3-phenoxypropyl acrylate and phenoxyethyl acrylate as essential components, and it is essential that 40% by weight to 90% by weight of phenoxyethyl acrylate is contained based on the total amount of monomers. Furthermore, the ink with the amounts of incorporation disclosed in this document, adheres only to polycarbonates, so that adhesiveness to multiple base materials cannot be obtained.
Japanese Patent Application Laid-Open Nos. 2008-247964, 2004-211057 and 2005-139017 disclose compositions containing isobornyl acrylate and N-vinyl caprolactam. However, these compositions are not for inkjet applications, but are used for optical fiber purposes.
As discussed above, there is a demand for an active energy ray-curable ink composition having good adhesiveness to various base materials and satisfactory ejection stability.